This invention relates generally to dynamoelectric machines and more particularly, to a method and system for determining the number of wedges required for a slot in the dynamoelectric machine.
Armature windings, also known as stator bar or rotor windings, are routinely inspected in at least some known electrical power generators, to verify their operation. In some known generators, a stator yoke in the generator surrounds an armature core and partially encloses the armature windings. The stator windings are formed from a plurality of copper conductors that are wound in the armature to form loops. The armature windings may be arranged within a stator slot in such a manner that desired voltage and current characteristics may be maintained by the generator during operation.
At least one known generator includes a wedge system to induce a radial retaining force (RRF) to the stator from wedges to facilitate reducing movement of the stator bar windings within the stator slot. However, if the wedge system itself becomes loose, the amount of RRF is reduced such that the stator bar windings may move during operation. Over time, the relative motion of the stator bar windings cause damage to insulation surrounding the stator bar wedges, and/or a potential stator bar winding failure through electrical shorts to ground. Accordingly, within known generators, the wedge system is periodically inspected to determine if any stator bar winding movement within the stator slots exceeds predetermined tolerances. Some machines may need a rewind operation where the windings and wedge system are replaced.
Currently, several known methods of determining the number of wedges per slot are employed. One known method involves hand calculations resulting in many different lengths of wedges. Another known method involves manually selecting wedges of various lengths and installing them until the slot is filled. All the previously known methods result in a high degree of slot-to-slot variation on the number and length of wedges used.